Sound-producing device



Jan. 8, 192.9. 1,698,296

w. BRANDEGGER v SOUND PRODUCING DEVICE Filed J an. 20, 1925 2 Sheets-Sheet l Jan. 8,

1,698,296 w. BRANDEGGER SOUND PRODUCING DEVICE 2 Sheets-Sheet 2 Filed Jan. 20, 1925 gmwcvzfww W W017 Patented Jan. 8, .1929.

UNITED STATES PATENT OFFICE.

WILIQ Y BRANDEGGER, OF STUTTGART, GERMANY, ASSIGNOR TO THE FIRM: EUGFIN GRILL, SPEZIALMASCHINENFABRIK, OF SALZWIESEN, ZUFFENHAUSEN-STUTT GART, GERMANY.

SOUND-PRODUCING DEVICE.

Application filed January 20, 1925, Serial No. 3,615, and in Germany July 5, 1924.

My invention relates to devices for producing acoustic vibrations, and more especially to devices in which a diaphragm is set vibrating by means of a flowing-medium such as. air under pressure.

In devices of this kind as heretofore constructed the continuous flow of the medium under pressure is transformed into sound waves by means of tongues or plate-shaped valves. All thesedevices require a very exact adjustment and are subject to failure if dust or other foreign matter settles down on them. Moreover it is very diflicult to remove the cause of failure and to render the devices operative again. Hand operation, for instance by means of a rubber bulb, is impracticable even for smaller sound intensities as the eflicien'cy of the transformation is comparatively low. I

I overcome these drawbacks by providing a diaphragm which cooperates after the manner of a valve with a seat surrounding the discharge opening for the flowing medium.

In the drawings aflixed to this specificatlon and forming part thereof, devices embodying my invention are illustrated diagrammatically by way of example.

In the drawings Fig. 1 is a similar view showing a devlce in whichthe diaphragm is free to vibrate 1n the casing,

I Fig. 2 is a similar view 'of a devlce in which one part of the casing is replaced by a sheet metal cover or the like.

Fig. 3 is an axial section, partly in elevation, showing a device adapted to'be operated by a rubber bulb,

Fig. 4 is a similar view showing a device in which the air supply and dischargep-ipes are arranged on the same side ofthe casing.

Figs. 5, 6, 7 and 8 illustrate various forms of diaphragms.

The new device may be operated. by any fluid under pressure supplied by suitable compressing means. As the device is very sensitive, it can be operated by means of a rubber bulb such as used for a bicycle horn,

but steam or some other fluid can be used as well. I

Throughout the drawings the diaphragm is marked .0, its perforations are marked 01', its seat is indicated by the letter 6. With the exception of Fig. 2, the parts of the casing are indicated by the letters a and b, and the supply and discharge pipes for the fluid by the letters a and b, respectively.

Referring first to Fig. 1, the casing consists of two parts a and b, which may be connected by threaded portions. The diaphragm a may consist of any suitable metallic ornonmetalhc material, for instance, steel, tombac, aluminium, bone, celluloid, fibre, or the like. It should be noted that the nature of the material employed for the diaphragm does not play any important role whatever and there is no necessity for using high-class material. A medium under pressure, such as air, is supplied to the casing through the pipe 0/. A discharge pipe 6 is formed on thepart b of the casing, its inner edge e surrounding the discharge opening and adjoining the middle portion of the diaphragm c which cooperates with this edge after the manner of a valve. This valve portion of the diaphragm is solid. -Perforations. d, whichmay be circular as shown in Fig. 6 or substantially rec tangular as shown in Fig. 7 or of any other suitable configuration, are formed in the marginal portions of the diaphragm at d. Instead of perforating the diaphragm, it

may be made partly cut away at the rim as shown inFig. 8, or star-shaped as shown in Fig. 5, or serrated as shown in Fig. 6, or it may be a solid disc. In the latter case, the air will flow past the outer edges of the diaphragm instead of flowing through the perforations.

Air supplied to the casing through the pipe a acts towards forcing-the diaphragm. onto its seat 6, whereupon the air escapes through the holes d. This causes the diaphragm to vibrate rapidly and these vibrations act towards producing loud sounds in the'discharge pipe I) and the sound tube (not shown). The volume and pitch of the sounds so produced are determined by the dimensions and proportions of the device, such as the size and weight of the diaphragm c, the size of the openings d, the distance of the diaphragm from its seat 0 in its normal or inoperative position,'and the volume of the chamber in the part a.

As shown in Fig. 1, the diaphragm 0' is allowed to vibrate freely between shoulders a and b'. formed on the parts a and b of the easing. The diaphragm may be left perfectly free within the space defined by the'shoulders or itmay be held loosely between them. If

i starting of the device often involves diificuldesired, the vibrations of the diaphragm can be damped by a layer of some suitable material which is preferably secured in the places Where the diaphragm is supported.

Obviously the casin may be of any suitable construction; for instance a sheet metal cover 7 or the like may be inserted in the part a as shown in .Fig. 2. Air under pressure is admitted through an opening f in the cover 7. I

Two further modifications are shown in Figs. 3 and 4. In both cases the diaphragm 0 which is perforated at dis held in the part a by a split ring 9 for instance a rubber ring. The part a is provided with a threaded sleeve and is screwed on the-part. b. The threaded portion of part b is provided with a slot or slots h which extends substantially at right angles to the axis of thethread. By this means the thread is deformed and an elastic reaction is obtained which tends to distort the 1 thread so that undesired relative movements of the parts is prevented even with the most severe shocks, while intentional adjustment is not interfered with. To facilitate such adjustment the threaded sleeve of the part a is serrated at i.

The seate for the diaphragm 0 is formed at the end of a nozzle is which is constructed on the principles on which musical instruments, such as the mouth-piece of a trumpet, are designed. A sound tube 0 is secured in the discharge ipe bof the part b.

A rubber bulb'Z is fastened on the supply pipe a of the part a. The end of this pipe is formed with a conical extension having a shoulder m at its free edge. By this means the aperture of the bulb Z is readily placed over the pipe 21 and retained by the shoulder m. This construction involves the advantage as compared with the well known expedient of a plurality of annular'projections, that a minimum stress is exerted on the bulb so that its life is increased and ordinary bulbs may be used.

In the modification shown in Fig. 4 the arrangement of parts is similar to that of Fig. 3 except for the fact that the supply pipe 25 is arranged on the same side of the casin which carries the discharge pipe 6, both plpes being integral with the part b, and part a being provided with a resilient cover n. The air from pipe 6 flows partly through the space between the diaphragm and its seat e on the nozzle is and partly through the openings d of the diaphragm. If the supply pipe is disposed on the front partb of the casing, I obtain the advantage of a'rigid connection being established between the supply pipe and the casin as is required to so support t e part b on a ve icle or the like that is not influenced by its vibrations.

If the walls of 'thecasing are rigid, the

ties so that special provisions must be made,

such as slow increase of pressure and very exact adjustment. In order to avoid this drawback the walls of the casing can be made resilient wholly or in part, for instance by reducing the thickness of a wall or of part thereof, or by inserting a resilient wall 11. as shown in Fig. 4. Instead of such a wall I may provide a second rubber bulb or the like. It is also possible to connect with the chamber surrounding the diaphragm another chamber or chambers which are partly resilient, such a chamber being for instance provided with in the casing which the diaphragm vibrates.

Another expedient for facilitatin the starting of the device consists in provi ing a hole in the casing connecting the chamber in which the diaphragm vibrates with the 'open air, such hole eing so small that the quantity of air escaping through it is negligible as compared with the quantity of air required or operation.

The adjusting of the device can be effected by other expedients than the screwin of one part of the casing on the other. For instance the nozzle k may be adjusted in relation to the diaphragm c by means of a threaded sleeve or by displacing this nozzle in some other way. A sleeve may be mounted on the pipe 6' in Figs. 3 and 4 and may be connected with the nozzle by means of a pin extending through a slot.

The volume of the chamber in front of the diaphragm may be varied by suitable means,

such as regulating screws or the like.

The means for displacing the nozzle is and for increasing the volume of the chamber are well known in the art and are therefore not described in detail.

.I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim 1. Sound producing device comprising a casing having an inlet and an outlet, a seat formed in said casing and a plate in said casing above said seat between said inlet and said outlet and being formed with perforations in the vibratory part intermediate the central and the outermost marginal portions of said plate.

' 2. Sound producing device comprising a casing having an air inlet and an air outlet, 9. seat in said casing and a plate arran ed in said casing between said inlet and out et for bodily displacement relative to said seat said platebeing solid in the central part to block the direct passage of air from said inlet to said outlet and apertured between said central part and its circumference.

3. Sound producing device comprising a casing having an air inlet and an air outlet, a seat in said casing and a plate arran ed in said casing between said inlet and out et for vibratory and free bodily movement relative in said casing between said inlet and outlet 10 t-o said seat, said plate'being solid in the cenfor bodily displacement relative to said seats, tral part to block the direct passage of air said plate being solid in the central part to from said inlet to said outlet and apertured block the direct passage of air from said inlet 5 between said central part and its ciroumferto said outlet and apertured between said cen-- ence. tral part and. its circumference. 15

4. Sound producing device comprising a In testimony whereof I aflix my signature. casing having an air inlet and an air out et,

two seats in said casing and a plate arranged WILI JY BBANDEGGER. 

